JPS6055316B2 - Manufacturing method of thermal recording head - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a thermal recording head used in a receiving section of a facsimile machine or the like.

Recently, the use of facsimile machines for transmitting documents and drawings using telecommunications technology has been rapidly progressing, and thermal recording type facsimile machines are attracting particular attention as inexpensive facsimile machines.

The most important part of these thermal recording systems is a thermal recording head, and methods for manufacturing these heads include a thin film system, a thick film system, and a monolithic system.

In both the thin film method and the thick film method, the substrate is made of alumina porcelain, beryllia porcelain, etc., with a thickness of 1.6 to 2", and the dimensions are 130 x 2.
A material with a thickness of about 20-mn is used, and in the monosilicon method, the substrate is made of n-type silicon. The resistors of the heating elements constructed on these substrates are Ta for the former two. N, SnO. , Pd/Ag base I, etc., are vapor-deposited or baked, and in the monolithic system, a transistor heating element is used, and the previous two
The protective layer on the surface of the device is made of SiC (SiC) glass or the like and baked at high temperature. However, those using conventional ceramic substrates have poor heat dissipation due to poor thermal conductivity, are large in size of about 300wn, and are difficult to obtain with good flatness, and are expensive. However, they have drawbacks such as poor processability and difficulty in manufacturing, and also have the drawback that n-type silicon substrates are expensive.

Conventional thin-film and thick-film heating resistors and conductor circuit parts (especially electrode parts) are generally manufactured using the screen printing method, which makes it difficult to obtain dimensional accuracy. Since the dimensional accuracy cannot be obtained, there is a drawback that heat generation varies.
Also, when manufacturing circuit patterns on ceramic substrates,
Since it is not possible to drill holes in the board, it is not possible to obtain a circuit with through-hole plating on both sides, so the circuit must be formed using a hybrid method or a multilayer method. There are disadvantages such as the need for firing in a high-temperature furnace, which makes it difficult to manufacture substrates, and the inability to perform subsequent drilling or bending. The present invention has been made in view of these points, and the first invention is based on iron, copper, aluminum, stainless steel,
The core is a metal plate with good thermal conductivity, such as an alloy plate, and an insulating layer is formed on the surface by lamination, painting, vapor deposition, etc., and at least a part of the surface is coated with an organic insulator with excellent heat resistance. A layer is formed, and on the heat-resistant insulating layer, linear heat-generating resistor film patterns are placed at regular intervals, and printed circuit electrodes with conductivity are placed on both sides of the film, sandwiching this film. The present invention relates to a thermal recording head. In addition, the second invention uses a metal plate with good thermal conductivity such as iron, copper, aluminum, stainless steel, or alloy plate as a core, and forms an insulating layer on the surface by thermal spraying of ceramic, and on the heat-reducing insulating layer. at a certain interval. The present invention relates to a thermal recording head in which a linear heat-generating resistor film pattern and electrode portions of a printed circuit sandwiching the film and having conductivity on both sides of the film are arranged. When voltage is applied to the electrodes of this heat-sensitive recording head, the resistive film between the electrodes generates heat, causing the heat-sensitive recording paper in contact with the electrodes to develop color and print.

The metal plate is 0.8-1.4T thick! About 0n is used to obtain a printed wiring board with a finished thickness of 1.6wn. When obtaining a double-sided printed wiring board with through-hole plating, pilot holes for through-hole plating are pre-drilled in the metal plate, and after pretreatment (roughening and rust prevention) for connection, these holes are filled with epoxy resin. Leave it to semi-harden.

Next, in the first invention, an insulating layer is formed by dip coating, powder coating, electrodeposition coating, etc. using a heat-resistant paint alone or in combination with a general paint. As heat-resistant paints, polyimide resins, modified polyimide resins, and other commercially available heat-resistant paints can be used, and as general-purpose paints, paints based on epoxy resins can be used.

In the second invention, the inorganic insulating layer is formed by ceramic plasma spraying.

α-alumina is an excellent ceramic material.
After forming the insulating layer, a hole is drilled in the center of the resin-filled hole to maintain insulation (for through-hole plating). A heat-generating resistor film can be formed on a heat-resistant insulating layer by adhering a metal alloy foil (nickel chrome, etc.) or by ion plating or chemical plating, or by using a general baking paste on an inorganic insulating layer. etc., by baking or vapor deposition. The pattern of the resistor film is formed by etching using a photographic method, or plating is performed after forming a resist mask using a photographic method. The resistor film pattern may be formed by this flash vapor deposition or die stamping method. To form a pattern including the electrode portion, the surface of the resistor film pattern portion is masked and then copper plating is performed on the entire surface by a conventional method to provide a copper plating layer with a thickness of about 20 to 35 p on the hole portion and the surface.

Next, a circuit pattern including electrode portions is formed using a photographic method to obtain a double-sided printed wiring board. After this, N
i-Au plating is applied, and other conductor parts are solder plated or provided with an insulating coating to prevent rust. When making a single-sided thermal recording head, the metal plate is processed in the same manner as above without drilling (because there is no through-hole plating), and then an insulating layer is formed.In particular, a resistor film pattern is formed on the heat-resistant insulating layer. A single-sided printed wiring board is formed by sandwiching this and forming a circuit pattern having conductive electrode portions on the side surfaces. After this, the electrode part is plated with Ni-Au, and the other pattern parts are subjected to anti-corrosion treatment. To make it multi-layered, an insulating layer (general or heat-resistant) is formed by laminating or painting on the parts other than the electrodes of this single-sided printed board, and then a circuit pattern is created and metal plated to establish continuity with the circuit below. This will result in multiple layers. The present invention will be specifically explained below based on the drawings.

FIG. 1 shows a thermal recording head having double-sided circuit patterns, in which a is a plan view, b is a cross-sectional view of an electrode portion (with a resistor film sandwiched therebetween), and c is a cross-sectional view of a through-hole portion. 1 is thickness 0 after pre-treatment (degreasing, roughening) for adhesion after drilling.
．． 8 to 1.2 Trrm metal plate such as iron plate, 2 is a heat-resistant laminated insulating layer, 3 is a laminated insulating layer, 4 is a resistance by etching of nichrome foil arranged linearly at regular intervals on the heat-resistant laminated insulating layer Body membrane pattern (width 60-150p, preferably 100p1, length 300-500p, preferably 400p1)
200 to 300 Ω), 5 is a conductor electrode part that is conductive on the side of 4 and is spaced at regular intervals, 6 is a circuit on the surface,
7 is a circuit on the opposite side, 8 is a through-hole plating part, and 9 is an insulating layer coated inside the through-hole.

When a voltage is applied between adjacent terminals of the electrode portion 5, the resistor film 4 sandwiched therebetween generates heat, and the heat-sensitive recording paper in contact therewith can develop color. FIG. 2 shows a single-sided pattern thermal recording head, in which a is a plan view and b is a cross-sectional view of the electrode portion.

1 is a metal plate such as an iron plate (0.8 to 1.2 Tr0it thickness) which has been pretreated for adhesion without drilling, and 10 is a heat-resistant polyimide resin coating (A). 1~0.2wrIn thickness)
, 11 is a resistor film pattern mainly made of nickel chromium (formed by etching a foil), 12 is a conductor electrode sandwiching 11 and conductive on its side, and 13 is a circuit pattern.

The resistor film patterns each have a resistance value of 200 to 300Ω, the conductor electrode 12 is plated with Ni-Au, and the circuit pattern 13 is plated with solder. FIG. 3 shows a thermal recording head having a curved surface and a single-sided printed board.

14 has a thickness of 1.4wr! It is an aluminum plate with a bent part at the end and a curved structure.

15 is a painted insulating layer of modified polyimide resin, 16 is a resistor 1
Resistor film pattern formed by electroless plating at 00Ω, 1
7 is a conductor electrode portion formed by an additive method (Cu plating → Ni plating → Au plating), and 18 is a mounting hole.

Figure 4 shows a thermal recording head with multiple circuit layers on one side, where a is a cross-sectional view of the electrode section, b is a plan view of the circuit pattern formed on one side, and c is b. Fig. 3 is a plan view of the stage where an epoxy insulating coating film is formed on the circuit pattern part excluding the resistor and electrode part, and d is a plan view after forming the circuit pattern on the insulating layer of c and making conduction with the land on the bottom surface. FIG. 3 is a plan view of a multi-layered stage. In a, 1 is a metal plate without holes, 19 is a heat-resistant insulating layer (thickness 0.1-0.2T)
1r! n), 20 is a general insulating layer, 21 is a 100-300Ω resistor film pattern formed by electroless plating,
22 is a conductor electrode section. In b, 23 is a circuit pattern, 24 is a land, and as shown in c, an insulating coating layer 25 made of epoxy resin paint is formed on the circuit pattern part excluding the resistor and electrode parts, and this insulating coating film A circuit pattern 26 is provided on top as shown in d, and a land 27 that is electrically connected to the land 24 is provided to form a two-layer thermal recording head. Figure 5 shows a thermal recording head in which an alumina layer formed by plasma spraying is used as a heat-resistant insulating layer.
A, b, and c are cross-sectional views showing manufacturing steps.

As shown in a, alpha alumina is deposited on a metal plate 1 such as an iron plate with a thickness of 1.4 w$t by plasma spraying in a small rectangular shape to a thickness of about 2 mm.
00p to form a heat-resistant insulating layer 28, and then ion plating is applied under vacuum on this layer or a paste is baked in a conventional manner to form a resistor film pattern arranged linearly at regular intervals. After 29 is formed, a general glass epoxy laminated insulating layer 30 is formed on one side at the same height as the ceramic 28 and on the entire other side as shown in b.

Then, as shown in c, a copper plating layer 3 is formed on the surface of the insulating layer 30.
After that, a circuit is formed on one side by a photographic method, and a multilayer circuit is formed by a lamination method or a hybrid method to obtain a thermal recording head made of a multilayer printed wiring board. Next, a method for manufacturing the thermal recording head of the present invention will be explained.

[Manufacturing method 1 (first invention)] A metal plate with or without holes is subjected to pretreatment for adhesion such as degreasing and roughening, and iron phosphate,
After imparting corrosion resistance through chemical conversion treatment such as zinc phosphate treatment, forming a heat-resistant insulating coating alone or a combination of a heat-resistant coating and a general coating, and then plating on the heat-resistant coating. By the method, resistor patterns having a constant resistance value are arranged in a straight line at regular intervals, and then the electrodes of a circuit pattern that can be electrically conductive are formed by sandwiching the resistor patterns on the side surfaces, or the electrode parts are first arranged at regular intervals. A conductive circuit pattern is formed on a heat-resistant coating film, and then a resistor having a certain resistance value is formed between the electrodes by plating or baking after painting to ensure continuity, and single-sided, multilayer, or double-sided printed wiring is created. A plate is obtained and then bent or unbent to form a thermal recording head.

Figure 6 shows an example of this manufacturing method, with A, b, c
FIG. 2 is a cross-sectional view showing the manufacturing process.

A metal plate 1 such as an iron plate with a thickness of 1.2 Tr0rL is made by drilling holes, degreasing the surface, roughening the surface with ferric chloride, giving it corrosion resistance by a conventional iron phosphate treatment, and then applying a polyimide liquid paint. A film with a thickness of 150p is formed on both surfaces by the dipping method of No. 32. After roughening the surface of this film by liquid honing, a metal-plated resistor film (with a thickness of 5
μ) Panel plating. Then, using a photographic method, patterns 33 are formed so as to be arranged at regular intervals and in a straight line (with a resistance value of 200Ω). Next, copper plating is performed (with the resist on the resistor pattern remaining) (to a thickness of 3?), and the panel plating is performed only on that side to ensure continuity on the side of the resistor pattern. Next, a circuit pattern is formed to form the electrode portion 34. First, a general single-sided circuit is formed.

At this time, if necessary, a resistor can be provided separately in the circuit section by printing or baking to obtain a multifunctional printed board. After covering the metal core printed wiring board obtained in this way with a solder resist film, heat generating electrodes are installed! The portion is curved to about 180rfnR so as to make good contact with the thermal recording paper to form a thermal recording head. According to this method, the insulating film layer is formed by painting, so it is easy to manufacture and can be obtained at a low cost.The resistor pattern is obtained by metal plating, so there is no need to bake it at high heat as in the conventional method 4. This has the advantage of high precision, and when combined with the use of a metal core, the overall cost is low and a thermal recording head with excellent heat dissipation properties can be obtained.

[Manufacturing method 2 (second invention)] Thickness 1.0-2. After pre-treating Chm's metal plates such as stainless steel, iron, copper, and aluminum plates for bonding, a part of the surface is coated with ceramic (
A thin film of .alpha.-alumina, etc.) is formed into a rectangular shape (thickness 100-200p), and conductive paste is baked on it in a straight line at regular intervals.

(Resistance value 100-300Ω) Next, apply a coating to form an insulating layer on the entire surface at the same height as the ceramic thin film (excluding the resistor film part). Roughen this surface (insulating layer) and then pre-plating treatment. After that, conductive copper plating is applied to the entire surface of the resistor film on the side surface of the resistor film (the surface of the resistor film should not be plated with resist). After that, a circuit is formed using the conventional photographic method, and one side is coated with copper plating. A multilayer or double-sided printed wiring board (with through-hole plating) is obtained.The board is then folded or not bent to form a thermal recording head.Figure 7 shows an example of this manufacturing method. , A, b, and c are cross-sectional views showing the manufacturing process.

Alumina plasma spraying 36 (200p) on a part of the surface of a surface-treated stainless steel plate (1.27m thick) 35
A heat-resistant insulating layer 36 is formed by forming a rectangular shape. On top of that, apply baking paste to resistor film pattern 37 (100Ω
). Then, an insulating layer 38 is formed by lamination to a thickness slightly lower than the sum of the thickness of this plasma insulating layer and the resistor pattern, and then copper plating is performed, and an electrode part 39 and a circuit pattern are formed by a conventional photographic method. Manufactures thermal recording heads. According to this method, a thin ceramic sprayed film is formed in a small area on a metal plate, and then a resistor film is formed on it by plating, vapor deposition, or baking of a paste, so it can be obtained at low cost. formation is possible even at high temperatures.

Furthermore, since it has a metal core, it has excellent heat dissipation properties, and has the effect that a thermal recording head can be obtained at a low cost. As explained above, the thermal recording head of the present invention uses a metal plate to obtain the thermal conductivity and heat dissipation properties of the substrate necessary for a thermal recording head, so it has better heat dissipation than conventional ceramic substrates. By changing the thickness of the insulating layer, desired thermal conductivity and heat dissipation properties can be obtained.

In addition, in order to provide a heating resistor, a particularly heat-resistant insulating layer is placed under the heating part of this resistor, so that when a voltage is applied to the electrode, the temperature of the resistor temporarily rises to about 300 degrees Celsius. Since the circuit pattern parts other than the electrodes can be provided with an inexpensive insulating layer, the cost of the insulating layer is not high. Conventionally, the heating resistor was baked on a ceramic substrate at a high temperature of about 800°C, but in the first aspect of the present invention, when an organic heat-resistant insulating material is used, an organic insulating layer that is heat-resistant at about 170 to 200°C is used. Since it can be formed by bonding a resistor foil thereon or by plating, it is easy to manufacture since there is no need to bake it at a high temperature.
As mentioned above, the board is made by forming an insulating layer on a metal plate core by lamination painting, etc., so the surface is smooth and large dimensions can be easily obtained, making it inexpensive. Since it is obtained by a photographic method (etched oil method), products with good dimensional accuracy can be obtained. In addition, the present invention allows for a double-sided printed wiring board system with through-hole plating, which eliminates the need for multi-layer circuits, and allows for drilling and bending processes that are absolutely impossible with conventional products, allowing for curved surfaces. It is also possible to obtain a heat-sensitive recording head that has good contact with the heat-sensitive recording paper. In addition, in the second aspect of the invention, in which an insulating layer is partially formed on a metal plate by ceramic spraying, it is possible to bake a resistor film in the form of a conventional paste, and it can be obtained at a low cost. As described above, the thermal recording head of the present invention can be easily manufactured using inexpensive metal plates and insulating materials, and therefore can be manufactured at a lower cost than those using conventional ceramic substrates.

[Brief explanation of the drawing]

1 to 4 show an embodiment of the thermal recording head of the present invention, in which FIG. 1a is a partially cutaway plan view, B, c
2A is a partially cutaway plan view, B is a sectional view of the main part, FIG. 3 is a perspective view, FIG. 4A is a sectional view of the main part, B
, c is a plan view, d is a partially cutaway plan view, Figs. 5 to 7
The figure shows the manufacturing process of the thermal recording head of the present invention.
FIGS. 5 a-c, 6 a-c, and 7 a-c show cross-sectional views, respectively. Explanation of symbols: 1...metal plate, 2...heat-resistant laminated insulating layer, 3... laminated insulating layer, 4...
...Resistor film pattern, 5...Conductor electrode part,
6... surface circuit, 7... opposite surface circuit,
8-...Through-hole plating, 9...Through-hole inner shaft insulating layer, 10...Heat-resistant coating film edge layer, 11...Resistor film pattern , 12...
...Conductor electrode part, 13...Circuit pattern, 14
... Aluminum plate, 15 ... Painted insulating layer, 16 ... Resistor film pattern, 17 ...
...Conductor electrode part, 18...Mounting hole, 19.
...Heat-resistant insulating layer, 20...Insulating layer, 2
DESCRIPTION OF SYMBOLS 1...Resistor film pattern, 22...Conductor electrode part, 23...Circuit pattern, 24...
...Land, 25...Insulating layer, 26...
...Circuit pattern, 27...7 land, 28.
...Heat-resistant insulating layer, 29...Resistor film pattern, 30...Insulating layer, 31...Copper plating layer, 32... Heat-resistant coating layer, 33...
... Resistor film pattern, 34 ... Conductor electrode part, 35 ... Stainless steel plate, 36 ... Heat-resistant insulating layer, 37 ... Resistor Membrane pattern, 3
8... Insulating layer, 39... Electrode part.

Claims (1)

[Scope of Claims] 1 a. A first step of pre-treating a metal plate, b. Using this metal plate as a core, powder coating is applied to both surfaces and hardened to form an insulating layer, or at least one surface is coated with powder. A second step of forming a heat-resistant insulating layer to obtain a substrate, c
After painting to form a plating base on the heat-resistant insulating layer,
The third step is to form linear heat-generating resistor films spaced at regular intervals by plating, d) sandwiching these resistor films and connecting them with electrodes that are electrically conductive on both sides of the resistor film and a printed circuit for supplying power. A method for manufacturing a thermal recording head comprising a fourth step of forming on a substrate. 2 a. The first step is to form a heat-resistant insulating layer by plasma spraying in a small quadrilateral shape on the metal plate, b. To form an insulating layer by powder coating on the metal plate other than these plasma sprayed areas. a second step of obtaining a substrate; c. a third step of forming resistor film patterns linearly arranged at regular intervals on this substrate by ion plating vapor deposition or paste baking;
Step d: A method for manufacturing a thermal recording head comprising a fourth step of forming on a substrate, sandwiching these resistor films, conductive electrode parts on both sides of the resistor film, and a printed circuit for connecting and supplying power. .